1. Field of the Invention
The present invention relates to memory cards, such as PC cards. A memory card includes board-mounted, packaged memory chips or surface-mounted memory chips (chip on board mounting) which are usually enclosed in a sealed, opaque package. The Personal Computer Memory Chip International Association (hereinafter PCMCIA) has set widely-used, standard specifications for PC cards.
Memory cards store data and can be interfaced for retrieval of that data by personal computers and other devices containing computers, such as telephone facsimile devices.
2. Background Art
One type of memory card is the One Time Programmable (hereinafter OTP) card. An OTP cards utilizes PROM memory chips and usually enclosed in a sealed cover. Once data is written to the PROM memory of an OTP card, the data cannot be erased and the card cannot be reprogrammed. Therefore, if the information in the PROM memory becomes obsolete for any reason, such as unforeseen compatibility problems or updates to the data, the OTP memory card must be discarded for a new memory card.
Another type of memory card is the Flash card. This type of memory card relies on flash EPROM devices that can be erased electronically upwards of 10,000 times through the computer interface of the Flash card. This allows a single Flash card to be reprogrammed many times for purposes such as applying an old card to a new application or debugging.
Flash cards, however, require more transistors per unit of memory storage. For this reason, Flash cards have a smaller capacity than a comparably sized OTP card. Also, the complexity of Flash card hardware can drive up the price.
Therefore, there is a need for an erasable and reprogrammable memory card with a simplified memory construction and high data storage capacity.